[unreadable] The skin has long been recognized as a preferred site for vaccination. With numerous resident dendritic cells (DCs), and accessory cells that have the capacity to secrete inflammatory and immunosuppressive mediators, the skin constitutes an ideal microenvironment to induce and control antigen-specific immune responses. Understanding the mechanisms of cutaneous immune function is critical for the future development of immunization strategies designed to generate and direct systemic immune responses. Efforts to understand cutaneous immunity have taken on a new urgency, as the development of effective vaccines and immunotherapies for the treatment of infections relative to biodefense (Category AC Pathogens) will in many cases require stimulation of durable cellular immunity capable of eliminating infected cells. Similarly, increasing evidence suggests that the development of effective immunotherapies for the treatment of HIV-1 infection will require induction of cellular immune responses capable of irradicating the reservoirs of infection in infected individuals. Importantly, several recent observations are challenging established models of cutaneous immune function. Taken together with previous data, these new studies suggest a novel working model for cutaneous immunity, which predicts that the function of cutaneous DCs is predetermined or "polarized" in the skin. The experiments we propose will test this model by genetically engineering the cutaneous microenvironment to create a DC1 polarizing environment and evaluating changes in the nature of the immune response that the model predicts. [unreadable] [unreadable] Genetic immunization has become an important tool for the induction and manipulation of the immune response, and has been broadly employed to initiate effective immune responses for the immunotherapy of tumors and the treatment and prevention of infectious diseases. While the precise events underlying the induction or suppression of the immune response remain to be clarified, skin appears to be an optimal target for genetic immunization strategies, and biolistic delivery of plasmid DNA to the skin is one of the most potent genetic immunization strategies described to date. However, although CTL responses can be detected, gene gun immunization results in a predominately Th2-skewed immune response. This presents a serious obstacle for the development and application of gene gun based immunization strategies. In the studies proposed here, we will utilize the gene gun to both deliver transgenic antigens and to genetically engineer the skin to create a DC1 polarizing microenvironment. Further, we will evaluate strategies to recruit DCs into a cutaneous environment where both antigen and DC1 polarizing cytokines is expressed. We will translate these studies to human skin using preclinical models designed as a direct prelude to human clinical trials. In addition to testing the proposed model, and further elucidating the mechanisms of cutaneous immunity, these studies have the potential to overcome a major limitation of cutaneous genetic immunization, enabling more efficient vaccination and immunotherapy for the treatment and prevention of tumors and infectious diseases. [unreadable] [unreadable] [unreadable] [unreadable]